Decontamination of prion-contaminated surfaces with phenols

ABSTRACT

A method of decontaminating a surface or liquid which is contaminated with prions includes treating the surface with a composition which includes one or more phenol. Phenols which are particularly effective include p-chloro-m-xylanol, thymol, triclosan, 4-chloro, 3-methylphenol, pentachlorophenol, hexachlorophene, 2,2-methyl-bis(4-chlorophenol), and p-phenylphenol.

BACKGROUND OF THE INVENTION

The present invention relates to the field of biologicaldecontamination. The invention finds particular application inconnection with the removal and/or destruction of harmful biologicalmaterials, such as prions (proteinaceous-infectious agents), frommedical, dental, and pharmaceutical instruments and will be describedwith particular reference thereto. It will be appreciated, however, thatthe method and system of the present invention may be utilized inbiological decontamination of a wide range of equipment, instruments,and other surfaces contaminated with prion infected material, such aspharmaceutical preparation facilities, food processing facilities,laboratory animal research facilities including floors, work surfaces,equipment, cages, fermentation tanks, fluid lines, and the like.

The term “Prion” is used to describe proteinaceous-infectious agentsthat cause relatively similar brain diseases in humans and/or inanimals, which are invariably fatal. These diseases are generallyreferred to as transmissible spongiform encephalopathies (TSEs). TSEsinclude Creutzfeldt-Jakob disease (CJD) and variant CJD (vCJD) inhumans, Bovine Spongiform Encephalopathy (BSE) in cattle, also know as“Mad Cow Disease,” Scrapie in sheep, and Wasting Disease in elk. All ofthese diseases attack the neurological organs of the animal or animalswhich are susceptible to the particular disease. They are characterizedby initially long incubation times followed by a short period ofneurological symptoms, including dementia and loss of coordination, andeventually death.

The infectious agent responsible for these diseases is thought to be asimple protein, with no associated nucleic acids. The pathogenicmechanism for such prion diseases is proposed to involve an initiallynormal host encoded protein. The protein undergoes a conformationalchange to an abnormal form (a prion), which has the ability ofself-propagation. The exact cause of this change is, at present,unknown. The abnormal form of the protein is not broken down effectivelyin the body and its accumulation in certain tissues (in particularneural tissue) eventually causes tissue damage, such as cell death. Oncesignificant neural tissue damage has occurred, the clinical signs areobserved.

Prion diseases may thus be classified as protein aggregation diseases,which also include several other fatal diseases, such as Alzheimer'sdisease and amyloidosis. In the case of CJD, the most prevalent priondisease in humans (occurring in roughly 1:1,000,000 of the population),about 85% of cases are thought to arise sporadically, about 10% arethought to be inherited, and about 5% arise iatrogenically.

Although not considered to be highly contagious, prion diseases can betransmitted by certain high-risk tissues, including the brain, spinalcord, cerebral spinal fluids, and the eye. Iatrogenic transmission hasbeen reported during several procedures, including dura-mater grafting,corneal transplants, pericardial homografts, and through humangonadotropin and human growth hormone contamination. Transmission viamedical devices has also been reported, including from neurosurgicalinstruments, depth electrodes, and other devices used for surgicalprocedures in close proximity to the central nervous system. Concernsare being raised that procedures previously considered to be “low risk”in terms of prion infection, such as tonsillectomy and dentalprocedures, may pose unacceptable risks of infection, particularly, ifthe incidence of prion-related diseases increases.

After a surgical procedure on a prion infected patient, prion containingresidue may remain on the surgical instruments, particularlyneurosurgical and ophthalmological instruments. During the longincubation period, it is extremely difficult to determine whether asurgical candidate is a prion carrier.

Different levels of microbial decontamination are recognized in the art.For example, sanitizing connotes free from dirt or germs by cleaning.Disinfecting calls for cleansing in order to destroy harmfulmicroorganisms. Sterilization, the highest level of biologicalcontamination control, connotes the destruction of all livingmicroorganisms.

It is now known that certain biological materials, which do not live orreproduce in the conventional sense, such as prions, are neverthelesscapable of replication and/or transformation into harmful entities. Weuse herein the term “deactivation” to encompass the destruction of suchharmful biological materials, such as prions, and/or their ability toreplicate or undergo conformational changes to harmful species.

Prions are notoriously very hardy and demonstrate resistance to routinemethods of decontamination and sterilization. Unlike microorganisms,prions have no DNA or RNA to destroy or disrupt. Prions, due to theirhydrophobic nature, tend to aggregate together in insoluble clumps.Under many conditions that lead to successful sterilization ofmicroorganisms, prions form tighter clumps, which protect themselves andunderlying prions from the sterilization process.

The World Health Organization (1997) protocol for prion deactivationcalls for soaking the instrument in concentrated sodium hydroxide orhypochlorite for two hours followed by one hour in an autoclave. Theseaggressive treatments are often incompatible with medical devices,particularly flexible endoscopes and other devices with plastic, brass,or aluminum parts. Many devices are damaged by exposure to hightemperatures. Chemical treatments, such as strong alkali, are damagingto medical device materials or surfaces in general. Glutaraldehyde,formaldehyde, ethylene oxide, liquid hydrogen peroxide, most phenolics,alcohols, and processes such as dry heat, boiling, freezing, UV,ionizing, and microwave radiation have generally been reported to beineffective. There is a clear need for products and processes that areeffective against prions yet compatible with surfaces.

Ernst and Race (J. Virol. Methods 41:193-202 (1993)) describe a study inwhich a phenol-based disinfectant product (LpH™, obtainable from STERISCorp., Mentor, Ohio), which according to the authors, containsp-tertiary-amylphenol, o-benzyl-p-chlorophenol, and 2-phenyl phenol, wasfound to be effective against scrapie. The study investigated theeffects of concentration (0.9-90%) and exposure time (0.5-16 hrs) on thelevel of infection removed in scrapie-sensitive hamster models injectedwith hamster brain homogenate. Relatively high concentrations of LpH™ orextended periods were found to be effective in reducing the presence ofthe prion. In other studies, phenols have generally been found not to beeffective against prions.

The present invention provides a new and improved method of treatment ofsurfaces contaminated with prion-infected material, which overcomes theabove-referenced problems and others.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a method oftreating a body which is contaminated with prions. The method includescontacting the body with a composition comprising a phenol to inactivateprions on the body.

In accordance with another aspect of the present invention, a method ofdetermining the effectiveness of a phenol-based decontaminantcomposition on a material which is contaminated with prions is provided.The method includes combining a solution of the phenol-baseddecontaminant with a protein material, determining a measure of thephenol taken up by the material, and determining the effectiveness ofthe composition based on the amount of phenol taken up.

One advantage of the present invention is that it is gentle oninstruments.

Another advantage of the present invention is that it deactivates prionsquickly and effectively.

Another advantage of the present invention is that it is compatible witha wide variety of materials and devices.

Still further advantages of the present invention will become apparentto those of ordinary skill in the art upon reading and understanding thefollowing detailed description of the preferred embodiments.

The following abbreviations are used throughout:

-   -   BSA=bovine serum albumin    -   OBPCP=o-benzyl-p-chlorophenol    -   OPP=o-phenylphenol    -   PCMX=p-chloro, m-xylanol    -   PTAP=p-tertiary-amylphenol    -   3,4DiOH benzoic=3,4 dihydroxybenzoic acid    -   3,5 DiMeOphenol=3,5 dimethoxyphenol    -   2,6 DiMeOphenol=2,6 dimethoxyphenol    -   2,3 DiMe-phenol=2,3 dimethoxyphenol

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take form in various components and arrangements ofcomponents, and in various steps and arrangements of steps. The drawingsare only for purposes of illustrating a preferred embodiment and are notto be construed as limiting the invention.

FIG. 1 is a plot showing Log reduction prions vs. the partitioncoefficient for various phenols;

FIG. 2 is a plot showing the correlation between partition coefficientsobtained by different methods;

FIG. 3 is a plot showing the effect of temperature on the reduction ofprions by phenols;

FIG. 4 is a plot showing the interactions of various phenols with BSA;

FIG. 5 is a plot of the percentage of initial concentration absorbed vsthe HPLC retention time of various phenols; and

FIG. 6 is a plot of phenol equivalents absorbed vs Log P_(c) for variousphenols.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A disinfectant composition, which is effective on a wide range ofbodies, including surfaces and liquid bodies, for reduction orelimination of hazardous prions includes a phenol or combination ofphenols. Surfaces for which the composition is effective at removing orsubstantially reducing the prion contamination include surfaces ofinstruments employed in medical, dental, and pharmaceutical procedures,surfaces of equipment used in the food and beverage processing industryand work surfaces, walls, floors, ceilings, fermentation tanks, fluidsupply lines, and other potentially contaminated surfaces in hospitals,industrial facilities, research laboratories, and the like. Particularexamples include the treatment of medical waste, such as blood, tissueand other body waste, prior to disposal, treatment of rooms, cages, andthe like used for housing animals known or suspected to be infected withprions, decontamination of BSE infected areas, includingslaughterhouses, food processing facilities, and the like, medicaldevice reprocessing, decontamination of disinfection or sterilizationsystems, formulation of pharmaceuticals, medicaments, and cleaningagents having antifungal, antiviral, antituberculoidal, andantibacterial efficacy, as well as prion efficacy.

The composition includes one or more phenols. Suitable phenols includealkyl, chloro, and nitro-substituted phenols and biphenols, andcarboxylic acids thereof. Exemplary phenols include, but are not limitedto phenol; 2,3-dimethylphenol; 3,5-dimethoxyphenol (3,5 DiMeOphenol);2,6-dimethoxyphenol (2,6 DiMeOphenol); o-phenylphenol (OPP);p-tertiary-amylphenol (PTAP); o-benzyl-p-chlorophenol (OBPCP); p-chloro,m-cresol (PCMC); o-cresol; p-cresol; 2,2-methylenebis(p-chlorophenol);3,4-dihydroxybenzoic acid (3,4DiOH benzoic); p-hydroxybenzoic acid;caffeic acid; protocatechuic acid; p-nitrophenol; 3-phenolphenol;2,3-dimethoxyphenol (2,3 DiMe-phenol); thymol; 4 chloro,3-methoxyphenol; pentachlorophenol; hexachlorophene; p chloro-m-xylanol(PCMX); triclosan; 2,2-methoxy-bis(4-chloro-phenol); andpara-phenylphenol.

It has been found that phenols with a relatively high hydrophobicitytend to be more effective in the composition. P_(c) is defined as thecalculated octanol-water partition coefficient. Higher Log P_(c) valuesindicate the substance is more hydrophobic. Software available fordetermining P_(c) values is available for example from AdvancedChemistry Development Software. Preferably at least one of the phenolsin the composition has a Log P_(c) value of at least 2.5, morepreferably, at least about 3, and up to about 6.0, as measured by theACD software method. It has been found that the higher the Log P value(more hydrophobic) the more phenol is absorbed. Accordingly, lowerphenol concentrations can be used when the phenol is hydrophobic toachieve the desired prion destruction. One particularly preferred phenolhaving a Log P_(c) value of 3.35 is PCMX.

The composition is preferably acidic, i.e., has a pH of neutral (pH 7),or below, more preferably, a pH of about 6, or above, most preferably, apH of about 2.5. For example, the composition may include an organic orinorganic acid which is added to adjust the pH, such as hydrochloricacid, glycolic acid, phosphoric acid, or the like. It is alsocontemplated that the composition may be alkaline, for example, a baseis added to adjust the pH, such as sodium hydroxide, potassiumhydroxide, or the like. Preferably the alkalinity is such that no morethan 50% of the phenol is ionized.

The composition includes water or other suitable solvent. Thecomposition is preferably provided as a concentrate, which is diluted inwater to form a decontaminant solution of a suitable concentration fordecontamination. Preferably, the concentrate is diluted to about a 1% byweight of the solution. For more rigorous decontamination, theconcentrate can be used at higher concentrations, e.g., at about 5% byweight of the solution, or more. Unless otherwise specified, allconcentrations are provided for the concentrate.

Preferably, the total molar phenol concentration of the concentrate isabout 0.1M-11.0M, or greater, more preferably, about 0.2M, or greater,and most preferably, about 0.5M, or greater. Effective compositionswhich destroy at least 99% of harmful proteins (e.g., prions) have beenformulated with total phenol concentrations of about 0.2M-0.5M, orgreater.

The composition may also include other ingredients, depending on thespecific application. Suitable ingredients include sequestering agentsfor removing water hardness salts, cosolvents, surfactants, corrosioninhibitors, buffering agents, and the like.

The sequestering agent is preferably an organic acid, inorganic acid, ora mixture thereof. Suitable organic acids include mono- and di-aliphaticcarboxylic acids, hydroxy-containing organic acids, and mixturesthereof. Exemplary sequestering agents include glycolic acid, salicylicacid, succinic acid, lactic acid, tartaric acid, sorbic acid, sulfamicacid, acetic acid, benzoic acid, capric acid, caproic acid, cyanuricacid, dihydroacetic acid, dimethylsulfamic acid, propionic acid,polyacrylic acid, 2-ethyl-hexanoic acid, formic acid, fumaric acid,1-glutamic acid, isopropyl sulfamic acid, naphthenic acid, oxalic acid,valeric acid, benzene sulfonic acid, xylene sulfonic acid, citric acid,cresylic acid, dodecylbenzene sulfonic acid, phosphoric acid, boricacid, phosphoric acid, and combinations thereof, with glycolic acidbeing preferred. For alkaline compositions, the acid sequestering agentmay be omitted.

The acid is preferably present at a concentration of about 2-25% of theconcentrate composition, more preferably, about 5-20%, more preferably,about 15-20%.

Suitable cosolvents include polyols containing only carbon, hydrogen andoxygen atoms. Exemplary polyols are C₂ to C₆ polyols, such as1,2-propanediol, 1,2-butanediol, hexylene glycol, glycerol, sorbitol,mannitol, and glucose. Higher glycols, polyglycols, polyoxides andglycol ethers are also contemplated as co-solvents. Examples of theseinclude alkyl ether alcohols such as methoxyethanol, methoxyethanolacetate, butyoxyethanol (butyl cellosolve), propylene glycol,polyethylene glycol, polypropylene glycol, diethylene glycol monoethylether, diethylene glycol monopropyl ether, diethylene glycol monobutylether, tripropylene glycol methyl ether, propylene glycol methyl ether,dipropylene glycol methyl ether, propylene glycol methyl ether acetate,dipropylene glycol methyl ether acetate, ethylene glycol n-butyl ether,1,2-dimethoxyethane, 2-ethoxy ethanol, 2-ethoxy-ethylacetate, phenoxyethanol, and ethylene glycol n-propyl ether. Combinations of co-solventsmay be used. The polyol is preferably present as a concentration of atleast 10%, more preferably, at least 20% and can be up to 40%.

Suitable surfactants include, anionic, cationic, non-ionic, zwitterionicsurfactants. Anionic surfactants, such as alkylaryl anionic surfactantsare particularly preferred. Exemplary surfactants include dodecylbenzenesulfonic acid and sodium 1-octane sulfonate, and combinations thereof.

Also useful anionic surfactants are sulfates, sulfonates, particularlyC₁₄-C₁₈ sulfonates, sulfonic acids, ethoxylates, sarcosinates, andsulfosuccinates such as sodium lauryl ether sulfate, triethanolaminelauryl sulfate, magnesium lauryl sulfate, sulfosuccinate esters,ammonium lauryl sulfate, alkyl sulfonates, sodium lauryl sulfate, sodiumalpha olefin sulfonates, alkyl sulfates, sulfated alcohol ethoxylates,sulfated alkyl phenol ethoxylates, sodium xylene sulfonate, alkylbenzenesulfonates, triethanolamine dodecylbenzene sulfonate, sodiumdodecylbenzene sulfonate, calcium dodecylbenzene sulfonate, xylenesulfonic acid, dodecylbenzene sulfonic acid, N-alkoyl sarcosinates,sodium lauroyl sarcosinate, dialkylsulfosuccinates, N-alkoyl sarcosines,lauroyl sarcosine, and combinations thereof.

The composition may also include one or more soluble inorganic salts,such as sodium chloride. Sodium chloride has been found to increase theeffectiveness of certain phenols, particularly those which are nothalogenated, such as OPP, while the effect on halogenated phenols, suchas PCMX, is less marked.

An exemplary concentrate composition is as follows: Ingredient % byWeight of Composition Water Q.S., typically, about 35.0% Sequesteringagent, e.g., Glycolic acid   0-25%, preferably, about 18.0 Surfactants,e.g., Dodecylbenzene   2-10%, preferably, about 7.0% Sulphonic acidSodium C₁₄-C₁₆   3-10%, preferably, about 6.0% Sulfonate Cosolvent,e.g., Hexylene Glycol  10-40%, preferably about 24.0% Phenols, e.g.,OBPCOP   2-15%, preferably, about 9.0% OBPCOP 0.2-5%, preferably about1.0%

In one embodiment, at least some of the OBPCOP or OBPCOP is replacedwith a phenol which is more effective than either of these phenols, suchas PCMX.

Such a composition has been shown to be effective againstprion-contaminated surfaces when diluted to a concentration of 1% byweight of the concentrate in water. While the mechanism of inactivatingprions is not fully understood, it is contemplated that the phenol mayform a complex with the prion protein, rendering it harmless. The prionis then unable to replicate to produce further prions. Studies by theinventors suggest that the phenol generally does not break down theprion. It is proposed that a change in the three dimensional structureof the prion protein results from interactions with the phenol,inactivating the prion.

Further, the composition is compatible with a wide range of surfaces, ascompared with conventional prion treatments, such as high temperaturesor high concentrations of sodium hypochlorite or sodium hydroxide.

The composition may be applied in a variety of ways, including byspraying, coating, immersion, or the like. In one embodiment, thecomposition is applied in the form of a gel. In this embodiment, athickening agent, such as a natural or modified cellulose, is added tothe formulation to increase the viscosity.

Other synthetic polymers, including polyacetates, natural gems,inorganic polymers such as synthetic clays, surfactants such as blockcopolymers and cationic surfactants may be used as a thickener.

The composition may be applied at room temperature, although highertemperatures are preferred. It has been found that by heating thecomposition to at least 30° C., more preferably, around 40° C., orabove, a substantial shortening in the time required for inactivation ofprions is achieved.

The effectiveness of various formulations of the composition may beinvestigated using human or other animal prion. Alternatively, a prionmodel, e.g., a protein such as bovine serum albumin (BSA) may be used toevaluate formulations. A preferred prion model is an ileal fluiddependant organism (IFDO). IFDO's were identified by Burdon, et al.(Burdon, J. Med. Micro., 29: 145-157 (1989)) and described as beingsimilar to prions in many respects, e.g., in resistance to disinfectionand sterilization methods. Due to the ability to culture IFDO'sartificially and detect them in the laboratory they provide a good modelsystem for studying the effect of decontamination processes on prioninactivation. In an exemplary embodiment, the IFDOs are artificiallycultured in a modified Mycoplasma base broth (Oxoid) and quantified byserial dilutions and plating on a similar agar. The efficacy of thedecontamination formulations is preferably studied by suspension testingat room temperature at about a 1% dilution of the concentratecomposition in water, simulating use of the composition. Followingsuitable contact times, aliquots are sampled and quantified by serialdilution and plating into modified Mycoplasma agar. The plates arepreferably incubated at about 37° C. for several hours, preferably about48 hours. The plates are examined and the number of colonies visible arecounted. Log reductions may then be determined (log reduction is ameasure of the number of organisms removed expressed as the differencebetween the Log₁₀ of the initial number of organisms minus the Log₁₀ ofthe number of organisms after treatment. E.g., a 6 log reduction meansthat out of one million initial organisms a maximum of one remains aftertreatment).

Breakdown studies with bovine serum albumin (BSA) using SDS-PAGEtechniques show that the BSA is not broken down to any significantextent by the disinfectant LpH™. It has been proposed, therefore, thatLpH™ and other phenol-based compositions have a subtle effect on thesecondary or tertiary structure of the protein, rendering it no longerharmful.

It has been found that the solubility of the phenol in the compositionhas an effect on the degree to which the protein is complexed. Ingeneral, the lower the solubility of the phenol in the formulation, thegreater the degree of complexation—i.e., the more effective the phenolformulation is at prion inactivation. Solubility is affected by thechoice of phenol and the type and concentrations of other ingredients inthe formulation, e.g., the solvents and cosolvents used.

Without intending to limit the scope of the present invention, thefollowing Examples show the effects of various disinfectant compositionson a simulated prion model.

EXAMPLES Example 1 Study of the Effect of Phenol Concentration on theEffectiveness of the Composition

To test the contribution of various formulation effects on the priocidalactivity of various compositions experiments are performed using IFDOlog reduction as the response. The ingredients of compositions I-VII arelisted in Table 1. Composition I is a commercial formulation, LpH™.

The IFDOs are artificially cultured in a modified Mycoplasma broth andquantified by serial dilutions and plating on a similar agar. Theefficacy of the compositions I-VII is studied by suspension testing atroom temperature at a 1% dilution of the composition in water. Followinga suitable contact time, e.g., 10 minutes, aliquots are sampled andquantified by serial dilution and plating into modified Mycoplasma agar.Following incubation at 37° C. for 48 hours, the plates are evaluated bycounting visible colonies and log reductions are determined. Resultswith the compositions are compared with an existing phenolic product areshown in Table 1. TABLE 1 % By Weight of Component in ConcentrateIngredient I II III IV V VI VII VIII Water 35.00 41.90 41.00 47.00 34.9040.00 35.90 37.95 Glycolic 18.00 18.00 18.00 18.00 18.00 18.00 18.0018.00 Acid Dodecyl- 7.00 7.00 7.00 7.00 14.00 14.00 7.00 10.50 benzeneSulfonic acid Sodium 6.00 12.00 12.00 6.00 12.00 6.00 6.00 9.00 C14-C16Sulfonate Hexylene 24.00 12.00 12.00 12.00 12.00 12.00 24.00 18.00glycol o-Benzyl-p- 9.00 9.00 9.00 9.00 9.00 9.00 9.00 6.00 Chlorophenolo- 1.00 0.10 1.00 1.00 0.10 1.00 0.10 0.55 Phenylphenol Log 5.1 4.8 4.95.2 5.7 4.8 6.7 5.2 Reduction*Initial count: log₁₀ 6.7 per mL.

A comparative study with LpH™ gave a Log reduction of 4.0 IFDO aftertreatment. Based on the Log Reductions obtained, Example VII was thebest, since a 6.7 Log Reduction was obtained (i.e., no visiblecolonies).

Example 2 Effect of Approximately Equimolar Concentrations of Phenols

Various phenols at approximately equimolar concentrations (wherepossible when solubility permitted) are studied by the method ofEXAMPLE 1. TABLE 2 shows the ingredients by weight for formulationsIX-XX and the results obtained. TABLE 2 Mol Molecular Phenol/ Ingredientwt 100 g IX X XI XII XIII XIV 2,3-Dimethylphenol 122.17 0.090 11.00o-Benzyl-p- 218.69 0.086 18.86 Chlorophenol o-Phenylphenol 142.58 0.08414.29 p-Chloro-m-Cresol 156.61 0.087 12.45 p-Chloro-m-Xylenol 150.20.099 15.50 2,4,5- 197.46 0.090 17.80 Trichlorophenol Hexylene Glycol4.00 3.95 6.29 4.21 4.00 4.23 iso-Propyl alcohol 8.00 7.90 7.62 8.148.40 8.08 Sodium 22.46 18.86 20.60 19.92 19.80 19.60 Laurylsulfate Alphaolefin 6.70 6.32 6.10 6.03 7.00 6.45 sulfonate Glycolic Acid 19.00 18.6817.14 18.30 21.00 18.00 Triethanolamine 2.50 1.43 0.95 1.34 1.40 1.02Soft Water 26.34 24.00 27.01 29.61 22.90 24.82 Log Reduction 4.1 4.7 4.84.3 4.4 4.9 Mol Molecular Phenol/ Ingredient wt 100 g XV XVI XVII XVIIIXIX XX 2,2-Methylenebis 122 0.051 6.17 (4-chlorophenol) Hexachlorophene406.9 0.026 10.56 p-Cresol 108.1 0.086 9.33 Phenol 94.1 0.090 8.46Thymol 150.2 0.090 13.52 Triclosan 289.4 0.056 16.18 Hexylene Glycol3.81 15.96 4.17 4.10 4.01 10.95 isopropyl 14.42 20.57 7.96 8.26 8.0020.79 alcohol Sodium 19.41 17.76 19.02 19.91 19.11 16.93 LaurylsulfateAlpha Olefin 7.26 12.70 6.26 6.28 6.29 3.98 Sulfonate Glycolic Acid22.14 18.38 18.00 17.92 18.00 11.81 Triethanolamine 1.48 1.45 1.00 1.001.00 0.68 Soft Water 25.31 2.62 34.26 34.07 30.07 18.68 Log Reduction3.8 3.6 3.7 3.6 3.2 2.7

Based on the Log values obtained, Formulation XIV with2,4,5-Trichlorophenol achieved the greatest Log Reduction (4.9) betterthan the Log Reduction (4.0) achieved with LpH.

Example 3 Correlation of Results with Partition Coefficients (P_(c))

P_(c) is defined as the calculated octanol-water partition coefficient.The log P_(c) values are calculated using two methods. The first methoduses Alchemy 2000 Molecular Modeling Software (Tripos) along with a dataset developed by STERIS Corporation. The second method uses AdvancedChemistry Development (ACD) Software Solaris v4.67 (© 1994-2002 ACD).The calculated log P_(c) values for each phenol are shown in TABLE 3:These values are compared with Log reduction colonies obtained inExample 2. TABLE 3 Log P_(c) (Alchemy Log₁₀ Reduction Phenol 2000) LogP_(c) (ACD) of Colonies Phenol 1.39 1.48 3.6 p-Cresol 2.08 1.94 3.72,3-Dimethylphenol 2.50 2.40 4.1 p-Chloro-m-cresol 2.58 2.89 4.3p-Chloro-m-xylenol 3.05 3.35 4.4 2,4,5-Trichlorophenol 3.23 3.71 4.9Thymol 3.27 3.28 3.2 o-Phenylphenol 3.40 2.94 4.8 2,2-Methylenebis(4-4.27 4.62 3.8 chlorophenol) o-Benzyl-p-chlorophenol 4.32 4.41 4.7Triclosan 4.51 5.82 2.7 Hexachlorophene 5.75 7.20 3.6

FIG. 1 shows the Log IFDO reduction vs Log P_(c) (Alchemy 2000) and theLog P_(c) (ACD) values. The correlation between the Log P_(c) (Alchemy2000) and the Log P_(c) (ACD) values is shown in FIG. 2.

Except for Triclosan and thymol, the activity of the phenols appear tocorrelate with the log P_(c) associated with the phenol.

Thymol and Triclosan were not included in this graph and the subsequentgraph due to their apparent lack of fit. The two methods for calculatinglog P_(c) agree fairly well with each other.

In general, phenols having a log P_(c) value between 2 and 6.5, asmeasured by either of the above methods, display enhanced activity.

The phenols in the LpH™ product were found to be the most significantrequirement for efficacy and were rated as OBPCP>>OPP>PTAP. When testedwith equivocal concentrations of these phenols, the optimal combinationswere shown to be formulation containing either OPBCP or OPP; PTAP wasless effective.

The effect of phenols against prions does not appear to involvebreakdown of the protein. This was shown in protein breakdown studieswith BSA by SDS-PAGE. On exposure to the phenol formulations the proteinappeared intact. It may be concluded that phenols have an unexpectedsubtle effect on the secondary or tertiary structure of the prionprotein or in some way renders them non-infectious.

Example 4 Effect of Temperature on Phenol Formulation Activity

The IFDO's are artificially cultured in a modified Mycoplasma broth andquantified by serial dilutions and plating on a similar agar. The effectof temperature on phenol formulation activity is studied by suspensiontesting at a 1% dilution of the composition in water at varioustemperatures (20 and ₄₀° C.) Following 5, 10, 15 and 20 minute contacttimes, aliquots are sampled and quantified by serial dilution andplating into modified Mycoplasma agar. After incubation at 37° C. for 48hours, the plates are evaluated by counting visible colonies and logreductions are determined. Results comparing the phenol composition(LpH) at 20 and 40° C. are shown in FIG. 3.

As shown in FIG. 3, IFDO levels were reduced to below detectable levels(i.e., greater than 1 Log) in 5 minutes at 40° C., as compared to 15minutes at 20° C.

Example 5 Interactions of Phenol Formulations with BSA Protein

Phenol solutions with different phenols were prepared as follows: about1.38 grams of a mixture of a phenol with solubilizers, such as anionicsurfactants, an organic acid, isopropyl alcohol, glycols, and an aminewas dissolved in 99 mL of water to form a solution containing a totalphenol concentration of 4 mM. About 1 g of BSA was added to the phenolsolution to give a concentration of about 0.15 mM BSA (the molecularweight of BSA is presumed to be about 66,000 Daltons). The solution wasstirred for 15 minutes and then centrifuged at 1800 rpm for fiveminutes. Aliquots were analyzed by high performance liquidchromatography (HPLC). FIG. 4 shows the results for 4 runs in terms ofthe percent of the initial phenol present which was absorbed by the BSA.The percent absorbed showed good correlation with the amount ofprecipitate which formed. Based on these results, the % absorption is agood way of determining a phenol's effectiveness against prions.

Example 6

The percentages of initial concentration absorbed from Example 5 wereplotted against the HPLC retention time of the phenol. FIG. 5 shows thecorrelation between these values. A correlation coefficient of 0.81 wasobtained, suggesting that HPLC retention time is a fairly good predictorof the absorption of phenol by the protein.

Example 7

Log P_(c) (computer calculated) values for several phenols were plottedagainst equivalents absorbed, as shown in FIG. 6. The results show thatthe higher the Log P value (more hydrophobic) the more phenol isabsorbed. Accordingly, lower phenol concentrations can be used when thephenol is hydrophobic to achieve the desired prion destruction.

Example 8

100 mL of water with varying amounts of brine and phenol were studiedfor phenol uptake. The results are shown in Table 4. The excipientincluded a mixture of surfactants. TABLE 4 Ex- Phenol- cipient Conc (%BSA (% by Phenol % of Run Temp Brine Phenol by wt) Ratio wt) Uptakeinitial 1 35 0 OPP 1 30 0.8 1.47 95.2 2 27.5 2.5 OPP 1.25 26 2.4 18.4230.4 3 20 5 OPP 1 22 4 16.66 25.5 4 35 5 PCMX 1.5 22 0.8 15.38 29.1 5 200 PCMX 1.5 30 4 26.74 11.2 6 27.5 2.5 PCMX 1.25 26 2.4 21.43 17.8 7 35 0PCMX 1 22 4 15.34 30.2 8 27.5 2.5 PCMX 1.25 26 2.4 20.3 21.7 9 27.5 2.5OPP 1.25 26 2.4 18.16 30.8 10 20 0 OPP 1.5 22 0.8 7.58 66.3 11 20 5 PCMX1 30 0.8 21.46 30.4 12 35 5 OPP 1.5 30 4 25.48 15.4The results show that the presence of brine in the solution had asignificant impact on phenol uptake when present at 2.5% or 5% byweight.

The invention has been described with reference to the preferredembodiment. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations insofar as they come within thescope of the appended claims or the equivalents thereof.

1. A method of treating a body which is contaminated with prions, themethod comprising: contacting the body with a composition comprising aphenol to inactivate prions on the body.
 2. The method of claim 1,wherein the phenol includes at least one of the group consisting ofp-chloro-m-xylanol, thymol, triclosan, 4-chloro, 3-methylphenol,pentachlorophenol, hexachlorophene, 2,2-5 methyl-bis(4-chlorophenol),p-phenylphenol, and combinations thereof.
 3. The method of claim 2,wherein the composition further includes at least one of o-phenylphenoland o-benzyl-p-chlorophenol.
 4. The method of claim 3, wherein thephenol is at a concentration of at least 0.005M.
 5. The method of claim1, wherein the phenol is at a concentration of up to about 0.2M.
 6. Themethod of claim 1, wherein the phenol has a log P_(c) value of between 2and 6.5.
 7. The method of claim 6, wherein the phenol has a log P_(c)value between 2 and
 5. 8. The method of claim 6, wherein the phenol hasa log P_(c) value of at least
 4. 9. The method of claim 1, wherein thecomposition includes a phenol at a concentration of at least about 10%.10. The method of claim 1, wherein the composition includes a solubleinorganic salt.
 11. The method of claim 10, wherein the soluble saltincludes sodium chloride.
 12. The method of claim 11, wherein the sodiumsalt is present at a concentration of at least 2% by weight.
 13. Themethod of claim 1, wherein the phenol includes OPP in a solution thatincludes brine.
 14. The method of claim 1, wherein the phenol includesPCMX.
 15. The method of claim 1, wherein the phenol complexes with theprions and precipitates.
 16. The method of claim 15, wherein the phenolhas minimal solubility.
 17. The method of claim 11, wherein the phenolincludes o-phenylphenol.
 18. The method of claim 1, wherein the bodyincludes a surface and the method includes contacting the surface withthe composition comprising the phenol to inactivate prions on thesurface.
 19. A method of determining the effectiveness of a phenol-baseddecontaminant composition on a material which is contaminated withprions comprising: combining a solution of the phenol-baseddecontaminant with a protein material; and determining a measure of thephenol taken up by the protein material; and determining theeffectiveness of the composition based on the amount of phenol taken up.20. The method of claim 19, wherein the protein material includes atleast one of a prion-containing material and bovine serum albumin.